Duckbill seal with fluid drainage feature

ABSTRACT

Seal assemblies, generally for use in trocar assemblies, are provided for selectively promoting movement of fluid away from a central portion of the seal assemblies. In one exemplary embodiment, an inner surface of a seal body of the seal assembly is configured to selectively promote such movement of fluid away from the central portion of the seal body toward a peripheral portion of the seal body. While various configurations, geometries, and dimensions are discussed, one example of such a configuration includes locating a central portion of the seal body at a more proximal position than a peripheral portion of the seal body.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/771,263 filed on Jun. 29, 2007 and entitled “Duckbill Seal with FluidDrainage Feature,” which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

This application relates to trocar assemblies, and more particularly, toseal assemblies often used in trocar assemblies.

BACKGROUND OF THE INVENTION

Surgical procedures often require a surgeon to gain access to a cavityin a patient's body. Generally, when such a procedure is required, anincision is made in an exterior wall of the cavity and an instrument isinserted into the working channel created by the incision. One commoninstrument used in such a procedure is a trocar assembly. Trocarassemblies include a variety of components, but generally can include atrocar cannula, a trocar obturator, and a trocar housing. In manydesigns, in order to access the body cavity, the trocar cannula isdirected through the skin and the trocar obturator is inserted throughan interior lumen defined by the cannula. The trocar obturator is thenused to penetrate the skin, which has often already had an incision madein it with a scalpel or similar device, and access the body cavity. Morespecifically, in some designs, applying pressure against a proximal endof the trocar obturator allows a sharp point at a distal end of thetrocar obturator to be forced through the skin until it enters the bodycavity. Then, the trocar cannula is inserted through the perforationmade by the trocar obturator and the trocar obturator is withdrawn,leaving the inner lumen of the trocar cannula as a path to access thebody cavity from outside of the body.

The trocar housing can be joined to a proximal end portion of the trocarcannula, and further, the housing can define a working chamber with anopen distal end portion that is in communication with the interior lumenof the cannula. Just as the interior lumen can receive the obturator, itcan also receive other elongated surgical instruments such that theinstruments can be axially extended into and withdrawn from the cannulathrough the proximal end portion of the working chamber defined by thetrocar housing. For example, in order to allow a surgeon to more easilysee during a procedure, an endoscope can be inserted through the cannulaand proximal or into the body cavity.

It is common for a sealing assembly or sealing device to be used in thetrocar assembly. Sealing assemblies generally help prevent fluid or gasfrom escaping during surgical procedures. Such prevention is needed,especially during certain minimally invasive surgical procedures, inwhich an insufflation gas is used to expand a body cavity. However, itcan be difficult to maintain the internal gas pressure because duringthe course of the procedure instruments are typically passed into andout of the trocar assembly. Accordingly, a sealing assembly, and oftentwo sealing assemblies, are generally provided in the trocar assembly.The sealing assembly can seal against an outer surface of insertedinstruments and thus can prevent fluids and insufflation gas fromleaving and/or entering the body cavity through the trocar cannula.

In instances where two sealing assemblies are provided, the one that isa top, or proximal, seal is usually designed to seal around a surgicalinstrument when it is present, and the bottom, or distal, seal isusually designed for sealing the trocar cannula when the instrument isnot present. One type of distal seal is a “duckbill” seal. A duckbillseal assembly generally includes a pair of opposed valve members whichopen and close in much the same manner a duck opens and closes its bill.Further, they can include a straight wall angle which defines a flexpoint for the opening and closing of the assembly, or alternatively,they can include multi-angled walls that can serve the same purpose butthat can also have improved tear resistance and buckling prevention.

While such sealing assemblies are effective to prevent fluids andinsufflation gas from leaving and/or entering the body cavity throughthe trocar cannula, fluids that can accumulate on the seal can often bewiped onto the instruments when they are being inserted therethrough.This is especially problematic for instruments such as endoscopesbecause fluid is often wiped directly onto the camera lens and thusobscures the surgeon's view.

Accordingly, there is a need for a seal assembly that minimizes theaccumulation of fluids on surgical instruments passed into and out of atrocar assembly.

SUMMARY OF THE INVENTION

Trocars are generally provided having one or more seal assemblies forselectively promoting movement of fluid away from a central portion ofthe seal assemblies. In one embodiment, a seal assembly for use in atrocar assembly is provided and includes a seal body configured toselectively open the seal assembly in response to an object beinginserted into the seal body. In an exemplary embodiment, an innersurface of the seal body is configured to selectively promote movementof fluid away from a central portion of the seal body toward aperipheral portion of the seal body. In one embodiment, the centralportion of the seal body is located at a more proximal position than theperipheral portion of the seal body. Further, the inner surface of theseal body can be formed by any number of geometric shapes, but in twoexemplary embodiments, the inner surface of the seal body extends in asubstantially linear manner from the central portion to the peripheralportion, or alternatively, the inner surface of the seal body extends ina substantially arcuate manner from the central portion to theperipheral portion. In one embodiment, the seal assembly is a duckbillseal assembly.

In another embodiment of a seal assembly for use in a trocar assembly, aseal body having a longitudinal axis extending therethrough and atransverse plane substantially perpendicular to the longitudinal axis isprovided, as is a plurality of opposed seal elements extending distallyat an acute angle with respect to the transverse plane from a proximalend of the seal body. The opposed seal elements can include inner andouter surfaces that meet at a seal face located at a distal end of theseal body, and further, the opposed seal elements can be configured toselectively open and substantially close the seal face. In an exemplaryembodiment, the inner surfaces of the seal elements can be configured toselectively promote movement of fluid away from a central portion of theseal elements toward a peripheral portion of the seal elements at theseal face. In one embodiment, the central portion of each of the innersurfaces of the seal elements is located at a more proximal positionthan the peripheral portion of the seal elements at the seal face.Further, the inner surfaces of each of the seal elements can be formedby any number of geometric shapes, but in two exemplary embodiments, theinner surfaces extend in a substantially linear manner from the centralportion to the peripheral portion, or alternatively, the inner surfacesof each of the seal elements extend in a substantially arcuate mannerfrom the central portion to the peripheral portion. In anotherembodiment, the seal body can include one or more channels formed in thedistal end of the seal body and the one or more channels can be adaptedto receive fluid that is moved away from the central portion of the sealelements. In one embodiment, the seal assembly is a duckbill sealassembly. In yet another embodiment, the plurality of seal elements istwo seal elements.

In one embodiment of a trocar assembly, a cannula extending from ahousing is provided such that the housing and the cannula define aworking channel sized and configured to receive a surgical instrument.At least partially located in the working channel can be a sealassembly, and the seal assembly can include a seal body with alongitudinal axis extending therethrough and a transverse planesubstantially perpendicular to the longitudinal axis. Further, aplurality of opposed seal elements can extend distally at an acute anglewith respect to the transverse plane from a proximal end of the sealbody. The opposed seal elements can include inner and outer surfacesthat meet at a seal face at a distal end of the seal body such that theseal elements can be configured to selectively open and substantiallyclose the seal face. In an exemplary embodiment, the inner surfaces ofthe seal elements can be configured to selectively promote movement offluid away from a central portion of the seal elements toward aperipheral portion of the seal elements at the seal face. In oneembodiment, the central portion of each of the inner surfaces of theseal elements is located at a more proximal position than the peripheralportion of the seal elements at the seal face. Further, the innersurfaces of each of the seal elements can be formed by any number ofgeometric shapes, but in two exemplary embodiments, the inner surfacesextend in a substantially linear manner from the central portion to theperipheral portion, or alternatively, the inner surfaces of each of theseal elements extend in a substantially arcuate manner from the centralportion to the peripheral portion. In one embodiment, the seal assemblyof the trocar assembly is a duckbill seal assembly. While the trocarassembly can include one seal assembly, in another embodiment it caninclude two seal assemblies such that a second seal assembly can beproximally spaced from the first seal assembly, and further, similar tothe first seal assembly, the second seal assembly can also be configuredto selectively open and substantially close.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an isometric view of one exemplary embodiment of a trocarassembly;

FIG. 2 is an isometric exploded view of the trocar assembly of FIG. 1with one exemplary embodiment of a seal assembly;

FIG. 3 is a side cross-sectional view of the trocar assembly of FIG. 1taken at line T-T;

FIG. 4 is an isometric view of the exemplary embodiment of the sealassembly of FIG. 2;

FIG. 5 is a top perspective view of the seal assembly of FIG. 4;

FIG. 6 is a side view of the seal assembly of FIG. 4;

FIG. 7 is an isometric cross-sectional view of the seal assembly of FIG.4 taken at line S-S;

FIG. 8 is a side cross-sectional view of the seal assembly of FIG. 4taken at line S-S;

FIG. 9 is an isometric view of another exemplary embodiment of a sealassembly;

FIG. 10 is a top perspective view of the seal assembly of FIG. 9;

FIG. 11 is a side view of the seal assembly of FIG. 9;

FIG. 12 is an isometric cross-sectional view of the seal assembly ofFIG. 9 taken at line S′-S′; and

FIG. 13 is a side cross-sectional view of the seal assembly of FIG. 9taken at line S′-S′.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices disclosed herein. One or moreexamples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devicesspecifically described herein and illustrated in the accompanyingdrawings are non-limiting exemplary embodiments and that the scope ofthe present invention is defined solely by the claims. The featuresillustrated or described in connection with one exemplary embodiment maybe combined with the features of other embodiments. Such modificationsand variations are intended to be included within the scope of thepresent invention.

The trocar described herein includes a seal assembly that is constructedto provide for selective movement of fluid away from a central portionof a seal body toward a peripheral portion of the seal body. Thisselective movement is achieved by using various geometric configurationsto form the seal body. Movement of fluid away from the central portionof the seal body provides a number of advantages, including reducing theamount of fluid that can accumulate on the seal so as to be wiped ontoinstruments, such as an endoscope, as they are passed in and out of atrocar assembly during a surgical procedure.

Apart from the seal assembly, in accordance with the present disclosure,the general structure of the trocar assembly does not generally formpart of the present invention. As such, a person skilled in the art willcertainly appreciate that the present seal assembly can be adapted foruse with a variety of trocar assemblies without departing from thespirit of the invention disclosed herein. Further, although the sealassembly as disclosed is generally described as being a duckbill sealassembly for a trocar assembly, a person skilled in the art willappreciate that the designs discussed herein can be equally applied toany seal assembly, not just duckbill seal assemblies, and other devicesthat utilize seal assemblies or similar type components in order to atleast partially block off one portion of a device from another, not justtrocar assemblies.

Referring to FIGS. 1-3, a trocar assembly 100 can generally include atrocar cannula 102 and a trocar housing (or handle) 104. Further, thetrocar cannula 102 can define an interior lumen with an open proximalend portion and an open distal end portion. The proximal end portion canextend into and be mounted in a distal end portion 104 d of the trocarhousing 104. The trocar housing 104 can have an open proximal endportion 104 p that can define a working channel 106. In one embodiment,the working channel 106 can include a proximal seal assembly 108 atleast partially positioned therein. In an exemplary embodiment, theworking channel 106 can further include a duckbill seal assembly 10,10′, also at least partially positioned therein. As shown, for example,in FIG. 3, the duckbill seal assembly 10 is positioned distal to theproximal seal assembly 108 and allows for selective sealing of theworking channel 106 of the trocar housing 104. A person skilled in theart will recognize that while in an exemplary embodiment two sealassemblies are provided in the working channel 106, in other embodimentsone seal assembly, or more than two seal assemblies, can also be used inthe trocar assembly 100. Further, the proximal seal assembly 108 and theduckbill seal assembly 10, 10′ can be secured into a desired position,at least partially within the working channel 106 in a variety of ways,such as, by snap-fitting a crown ring 110 and a gasket ring 112together, and then securing the gasket ring 112 to the trocar housing104. A gasket retainer ring 114 can further secure the attachmentbetween the gasket ring 112 and the trocar housing 104. In oneembodiment the trocar housing 104 can further include a stop cock valve116 and a stop cock valve lever 118, which can work together to allowand/or prevent passage of an insufflation fluid or gas, e.g. carbondioxide, through flexible tubing into a portion of the trocar housing104 and the trocar cannula 102.

The proximal seal assembly 108 can be adapted to cooperate with anexterior of any instrument inserted at least partially through thetrocar cannula 102 such that it can sealingly engage the exterior of theinstrument and thus can prevent the passage of fluids through the trocarhousing 104 when the instrument is present within the trocar assembly100. All sorts of instruments, although primarily surgical instruments,can be inserted at least partially through the trocar cannula 102. Oneexample of such an instrument is an endoscope or a similar device thatenables visualization during minimally invasive surgical procedures. Oneskilled in the art will recognize that many other instruments are knownfor insertion into at least a portion of the trocar cannula 102, andaccordingly, that the proximal seal assembly 108 can likewise sealinglyengage the exterior of those instruments as well.

Referring broadly to FIGS. 4-13, a duckbill seal assembly 10, 10′ cangenerally include a seal body 12, 12′ with a proximal end 12 p, 12 p′and a distal end 12 d, 12 d′, a longitudinal axis L, L′ (FIGS. 6 and 11)extending through the seal body 12, 12′, and a transverse planesubstantially perpendicular to the longitudinal axis L, L′. The sealbody 12, 12′ can be configured to selectively open the seal assembly 10,10′ in response to an object being inserted into the seal body 12, 12′.Further, the proximal end 12 p, 12 p′ of the seal body 12, 12′ caninclude a circumferential flange 14, 14′ extending beyond a width of theseal body 12, 12′.

In one embodiment, the seal body 12, 12′ can be a unitary structure. Inanother embodiment, the seal body 12, 12′ can include a plurality ofopposed seal elements. In the illustrated embodiments, two seal elements16, 16′, 18, 18′ comprise the seal body. In other embodiments, three ormore seal elements can form the seal body. The seal elements 16, 16′,18, 18′ can extend distally at an acute angle with respect to thetransverse plane from the proximal end 12 p, 12 p′ of the seal body 12,12′. The seal elements 16, 16′, 18, 18′ can include a central portion20, 20′ and a peripheral portion 22, 22′, as well as inner surfaces 24,24′ and outer surfaces 26, 26′. In some embodiments, one or more ribs28, 28′, or other protruding structures, can be associated with theinner surfaces 24, 24′ to provide a variety of advantages includingadded stability, as is known to those skilled in the art. In anexemplary embodiment the inner surfaces 24, 24′ of the seal elements 16,16′, 18, 18′, can meet at the distal end 12 d, 12 d′ of the seal body12, 12′ to form a seal face 30, 30′, and further, the seal body 12, 12′and/or the seal elements 16, 16′, 18, 18′ can generally be configured toselectively open and substantially close the seal face 30, 30′.

In one aspect, inner surfaces 24, 24′ of seal elements 16, 16′, 18, 18′are configured such that they can selectively promote movement of fluidaway from the central portion 20, 20′ of the seal body 12, 12′ andtoward the peripheral portion 22, 22′ of the seal body 12, 12′. While avariety of configurations can be used to achieve this design goal, inone embodiment the central portion 20, 20′ can be positioned such thatit is more proximal than the peripheral portion 22, 22′. In other words,central portion 20, 20′ is raised proximally relative to the peripheralportion 22, 22′.

Before discussing the two illustrated embodiments in further detail, itshould be noted that although the illustrated embodiments include theseal assembly 10, 10′ with the seal body 12, 12′ and the seal elements16, 16′, 18, 18′, a person skilled in the art will recognize that thefeatures as discussed herein can be easily adapted for use in a unitaryseal body. However, for ease of reference, the invention will bedescribed in the context of a seal assembly that includes a seal body12, 12′ with seal elements 16, 16′, 18, 18′.

FIGS. 4-8 illustrate one embodiment as a seal assembly 10 that has innersurfaces 24 of the seal elements 16, 18 configured to selectivelypromote movement of fluid away from the central portion 20 of the sealelements 16, 18 and toward the peripheral portion 22 of the sealelements 16, 18 at the seal face 30. In this embodiment the centralportion 20 is more proximally positioned than the peripheral portion 22.Moreover, the inner surfaces 24 of each of the seal elements 16, 18extend in a substantially linear manner from the central portion 20 tothe peripheral portion 22 at the seal face 30. The height separation H₁(FIG. 8) between the proximal most portion of the seal elements 16, 18at the central portion 20 and the distal most portion at the peripheralportion 22 can vary. Generally, however, the height separation H₁ can bein the range of about 0.050 to 0.250 inches. In an exemplary embodiment,the height separation H₁ is about 0.128 inches. Because in thisembodiment, the inner surfaces 24 of seal elements 16, 18 extend in alinear manner, the orientation of the inner surfaces can also beexpressed as an angle. Although the angle at which the inner surfacesslope towards the peripheral portion 22 of the of the seal element canvary, the angle with respect to horizontal is generally in the range ofabout 10° to 25°. In an exemplary embodiment the angle is about 14°.

FIGS. 9-13 illustrate another embodiment in which the seal assembly 10′has an arced configuration such that inner surfaces 24′ of the sealelements 16′, 18′ are configured to selectively promote movement offluid away from the central portion 20′ of the seal elements 16′, 18′and toward the peripheral portion 22′ of the seal elements 16′, 18′ atthe seal face 30′. Although functionally similar to the embodiment shownin FIGS. 4-8, the embodiment of FIGS. 9-13 features a curved innersurface of the seal elements rather than one that is linearly orientedas in FIGS. 4-8. More specifically, the central portion 20′ is moreproximally positioned than the peripheral portion 22′. As shown, theinner surfaces 24′ of each of the seal elements 16′, 18′ extend in asubstantially arcuate manner from the central portion 20′ to theperipheral portion 22′ at the seal face 30′. In one embodiment, a heightseparation H₂ (FIG. 13) between the central portion 20′ and theperipheral portion 22′ of the seal body 12′ is in the range of about0.050 to 0.250 inches. In an exemplary embodiment, the height separationH₂ is about 0.155 inches. Because in the embodiment of FIGS. 9-13 theinner surfaces 24′ extend in a substantially arcuate manner, a radius ofthe resulting arc can be measured. Although, the radius can vary, theradius can be in the range of about 0.5 to 1 inch. In an exemplaryembodiment, the radius is about 0.772 inches.

Referring again to FIGS. 4-13, the distal end 12 d, 12 d′ of the sealbody 12, 12′ can include one or more channels 32, 32′ in peripheralregions 24, 24′ of seal that can receive fluid moved away from thecentral portion 20, 20′. One skilled in the art will recognize thatother mechanisms that can retain, store, and/or remove fluid that ismoved away from the central portion 20, 20′ out of the seal assembly 10,10′ can also be easily adapted for use in the seal assembly 10, 10′. Byway of non-limiting examples, fluid can be directly drained from theseal assembly 10, 10′ as it is removed from the central portion 20, 20′,or alternatively, the seal assembly 10, 10′ can include a suction tubethat is able to evacuate fluid out of the seal assembly 10, 10′. Asillustrated in FIGS. 9-13, the seal body 12′ can also optionally includeone or more chamfers 34′ located at the distal end 12 d′ of the sealbody 12′. At least one advantage provided by the chamfers 34′ is thatthey can prevent fluid from becoming trapped in corners of the channels32′. In the embodiment illustrated in FIG. 13, the chamfers 34′ areformed at about a 15 degree angle, although a variety of angles can beused with the chamfers 34′ to achieve similar results. It is understoodthat chamfers can also be included in the seal body 12 illustrated inFIGS. 4-8, as well as in other designs of seal assemblies that fallwithin the scope of this disclosure.

Additional features that enhance the performance of the seal assembly10, 10′ can also be incorporated into the devices as disclosed herein.For example, in one embodiment, the seal elements 16, 16′, 18, 18′ caninclude multi-angled surfaces, as more thoroughly discussed in UnitedStates Publication No. 2005/0077688 of Voegele et al., filed on Sep. 17,2004 and entitled “Multi-Angled Duckbill Seal Assembly,” which is herebyincorporated by reference in its entirety.

The seal body 12, 12′ can be made out a wide variety of materials. Forexample, in an exemplary embodiment, the seal body 12, 12′ can be madeof a polymer such as an elastomer, including, for example silicone orpolyisoprene. A person skilled in the art will appreciate othermaterials can be used in the formation of the seal assembly 10,10′, andparticularly the seal body 12, 12′ and/or the seal elements 16, 16′, 18,18′.

Further, although two different geometric designs are illustrated hereinas exemplary embodiments, a person skilled in the art will appreciatethat there are a variety of other designs that can also be incorporatedinto the seal assembly 10, 10′ that can selectively promote movement offluid away from the central portion 20, 20′ of the seal elements 16,16′, 18, 18′ toward the peripheral portion 22, 22′ of the seal elements16, 16′, 18, 18′ at the seal face 30, 30′. Similarly, the dimensionsdisclosed herein provide a range of possible dimensions for use in theexemplary embodiments, but a person skilled in the art will appreciatethat other dimensions can be used in similar devices to achieve similarresults. Many factors can affect design choices related to thegeometries, shapes, dimensions, and materials selected for use in asimilar seal assembly, such as the intended use, the ease ofmanufacturing, and the design of other assemblies that will be used inconjunction with the seal assembly 10, 10′. It is understood thatgeometries, shapes, dimensions, and materials not specifically disclosedherein do not depart from the spirit of the disclosed devices.Additionally, to the extent that linear or circular dimensions are usedin the description of the disclosed device, such dimensions are notintended to limit the types of shapes that can be used in the sealassembly. A person skilled in the art will recognize that an equivalentto such linear and circular dimensions can easily be determined for anygeometric shape. In a similar vein, although the designs disclosedherein illustrated a symmetrical design, in other embodiments, anon-symmetrical design can be used. Likewise, in one embodiment, a sealassembly can include at least one inner surface of a seal element thatextends in a substantially linear manner from a central portion to aperipheral portion of the seal element at a seal face and at least oneinner surface of a seal element that extends in a substantially arcuatemanner from a central portion to a peripheral portion of the sealelement at the seal face.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

1. A seal assembly for use in a trocar assembly, comprising: a seal bodyhaving proximal and distal ends with a longitudinal axis extendingtherethrough and a transverse plane substantially perpendicular to thelongitudinal axis, the seal body having a plurality of opposed sealelements, each having inner and outer surfaces and meeting at a sealface at the distal end of the seal body such that the seal face has acentral portion substantially aligned with the longitudinal axis of theseal body and a peripheral portion that is outwardly disposed from thecentral portion, the seal elements being configured to selectively openand substantially close the seal face; and a raised rib disposed on theinner surface of each of the plurality of opposed seal elements, theraised ribs being substantially aligned with the central portion of theseal face, wherein the inner surfaces of the seal elements areconfigured to promote movement of fluid away from the central portion ofthe seal face toward a peripheral portion of the seal face.
 2. The sealassembly of claim 1, wherein the central portion of each of the innersurfaces of the seal elements is at a more proximal position than theperipheral portion of the seal elements at the seal face.
 3. The sealassembly of claim 2, wherein the inner surfaces of each of the sealelements extend in a substantially linear manner from the centralportion to the peripheral portion of each of the seal elements at theseal face.
 4. The seal assembly of claim 2, wherein the inner surfacesof each of the seal elements extend in a substantially arcuate mannerfrom the central portion to the peripheral portion of the seal elementsat the seal face.
 5. The seal assembly of claim 4, wherein an arcextending across the peripheral portion of each of the inner surfaces ofthe seal elements and through the central portion of each of the sealelements has a radius in the range of about 0.5 to 1 inches.
 6. The sealassembly of claim 1, wherein the seal body further comprises one or morechannels formed in the distal end thereof and in communication with theinner surfaces to receive fluid moved away from the central portion ofthe seal elements.
 7. The seal assembly of claim 1, wherein theplurality of opposed seal elements is two seal elements.
 8. The sealassembly of claim 1, wherein the plurality of opposed seal elements meetat the seal face at the distal end of the seal body to define a singleopening extending substantially between two points on opposite sides ofthe seal body.
 9. The seal assembly of claim 1, wherein the sealassembly is a duckbill seal assembly.
 10. A trocar assembly, comprising:a housing having a cannula extending therefrom, the housing and thecannula defining a working channel sized and configured to receive asurgical instrument; a seal assembly at least partially located in theworking channel, the seal assembly comprising: a seal body havingproximal and distal ends with a longitudinal axis extending therethroughand a transverse plane substantially perpendicular to the longitudinalaxis, the seal body having opposed seal walls extending at an acuteangle with respect to the transverse plane from a circumferential flangeat the proximal end of the seal body to a seal face at the distal end ofthe seal body, the opposed seal walls meeting to form a seal face at thedistal end of the seal body, the seal face being selectivelyconfigurable between an open position that allows the passage ofinstruments and fluid through the seal face and a closed position thatprevents the passage of instruments and fluid through the seal face theseal face; a longitudinally extending raised rib disposed on the innersurface of each of the plurality of opposed seal walls, the raised ribsbeing disposed at a central portion of the seal face, wherein the innersurfaces of the seal walls are configured to promote movement of fluidaway from the central portion of the seal face toward a peripheralportion of the seal face.
 11. The trocar assembly of claim 10, whereinthe central portion of each of the inner surfaces of the seal elementsis at a more proximal position than the peripheral portion of the sealelements at the seal face.
 12. The trocar assembly of claim 11, whereinthe inner surfaces of each of the seal elements extend in asubstantially linear manner from the central portion to the peripheralportion of each of the seal elements at the seal face.
 13. The trocarassembly of claim 11, wherein the inner surfaces of each of the sealelements extend in a substantially arcuate manner from the centralportion to the peripheral portion of the seal elements at the seal face.14. The trocar assembly of claim 10, further comprising a second sealassembly proximally spaced from the first seal assembly, the second sealassembly being configured to selectively open and substantially close.15. The seal assembly of claim 10, wherein the plurality of opposed sealelements is two seal elements.
 16. The seal assembly of claim 10,wherein the plurality of opposed seal elements meet at the seal face atthe distal end of the seal body to define a single opening extendingsubstantially between two points on opposite sides of the seal body. 17.The trocar assembly of claim 10, wherein the seal assembly is a duckbillseal assembly.